Okay, so do you know what size the hard drive is? Because without extra faffing about with patches, OS 3 only supports up to 4GB. It will allow you to install more than that, but once you use any part of the drive over the 4GB mark it'll destroy data on it. But that's for another day. If you have no other way of getting things onto it, you'll at least need PC with a floppy drive to get the files onto a 720KB formatted MS-DOS floppy, and CrossDOS mounted to read it on the Amiga. Once that's there, download HDInst.lha, and the lha unpacker from Aminet, unpack it, run it and partition the drive. If it's bigger than 4GB, don't use anything past 4GB until you sort out the drivers/filesystems so they support it...
Edit: I see you have an A4000... Is that connected to the internet? If so, that'll make things *much* easier!